#include<stdio.h>
#include<string.h>
#pragma warning(disable:4996)
//HASH表来去重
int My_Find(char arr[], int sz)
{
	int count = 0;
	char tmp[128] = { -1 };
	for (int i = 0; i < sz; i++)
	{
		if (tmp[arr[i]] != arr[i]) {
			tmp[arr[i]] = arr[i];
			count++;
		}
	}
	return count;
}
int main()
{
	char arr[501] = { 0 };
	scanf("%s", arr);
	int sz = strlen(arr);
	printf("%d\n", My_Find(arr, sz));
	return 0;
}